Microspheres - Novel Drug Carriers

Abstract

Conventional drug delivery systems have a major disadvantage of frequent dosing to maintain the levels of the drug in the therapeutic region required to treat the disease. Controlled drug delivery systems were introduced to overcome the frequent administrations and increase patient compliance reducing the cost of treatment. Controlled release systems also helped in achieving the desired feature of delivering the drug at a predetermined rate and at the desired target. Many of these drawbacks can be overcome by the new drug carriers – Microspheres. Microspheres based drug delivery has gained great importance in recent time. The important feature of controlled release of microspheres comes from its nature of phase separation is the micro phase separation morphology which provides it with the characteristic of controlled rate of degradation and drug release.

Keywords

Microspheres, Conventional drug delivery, Drug Carriers, Sol gel, Biodegradable

Introduction

Conventional drug delivery systems have a major disadvantage of frequent dosing to maintain the levels of the drug in the therapeutic region required to treat the disease. Controlled drug delivery systems were introduced to overcome the frequent administrations and increase patient compliance reducing the cost of treatment [1].

The Biopharmaceutics Classification System (BCS) classifies class II and III compounds as the most desirable compounds to reduce the dosing frequency and side effects [2].

Controlled release systems also helped in achieving the desired feature of delivering the drug at a predetermined rate and at the desired target. Many of these drawbacks can be overcome by the new drug carriers – Microspheres [3].

Microspheres based drug delivery has gained great importance in recent time. The important feature of controlled release of microspheres comes from its nature of phase separation is the micro phase separation morphology which provides it with the characteristic of controlled rate of degradation and drug release [4].

Microspheres physically appear as small spherical particles with the diameter in micrometers range (1μm to 1000μm) and are also sometimes referred to as micro particles [5]

Advantages

• It is a very suitable method of delivery for poorly water soluble drugs [6]

• They exhibit the potential of controlled drug delivery which is desired characteristic of ideal dosage form [7]

• Microsphere drug delivery is suitable for drugs with poor bioavailability like that of Neostigmine Bromide and Zaleplon drugs [8,9]

• Radio immobilized microspheres can be used in quality treatment in cancer patients on whom all the other modes of treatment have failed [10]

• Microspheres are also characterized with features of prolonged in vivo half-life, decreased toxicity, improved patient compliance and increased stability [11].

Formulation Methods of Microspheres

Several methods are employed for the formulation of microspheres

• Emulsion Solvent evaporation method [12]

• Quasi-emulsion solvent diffusion method [13]

• Sol gel method [14]

• Solvo thermal reaction [15]

• Double – emulsion solvent extraction technique [16]

• Vibration technology [17]

Polymers

Wide range of polymers is employed in the formulation of microspheres of which some of them are:

• Biodegradable polymers: aliphatic polyesters; poly (lactide), poly (glycolide), poly-O- caprolactone (PCL) and their copolymers [18].

• Non Biodegradable polymers [19]:

a) Cellulose derivative: Carboxy methyl cellulose, Ethyl cellulose Cellulose acetate hydroxyl propyl methyl cellulose

b) Silicons: Polydimethyl siloxane, Colloidal silica, Polymethacrylate, Polymethyl methacrylate

c) Others: Poly vinyl pyrolidine, Ethyl vinyl acetate, Poloxamine etc...

Application of Microspheres

• Targeted Tegaserod Maleate microspheres for Colonic diseases [20]

• Use of Yttrium-90 Microspheres for Treatment of Hepatic Malignancy [21]

• Gastro retentive microspheres for the delivery of Verapamil Hydrochloride [22]

• Magnetic Microspheres are used in evaluating biophysical parameters of human blood [23]

• Discovery of Insulin Loaded Eudrajit Microspheres has been a great milestone for the treatment of diabetis [24]

• Metoclopramide Hydrochloride drug which is characterized with short half life is formulated as Sustained release microsphere and thus extending the release of the drug from the drug delivery system [25]

Acknowledgement

This content of the article is scrutinized and approved by M. Murali and written by Pratibha Muntha

References

1. Fentie M, Belete A, Mariam TG.Formulation of Sustained Release Floating Microspheres of Furosemide from Ethylcellulose and Hydroxypropyl Methylcellulose Polymer Blends. J NanomedNanotechnol. 2015;6:262.
2. Enriquez GG, Orawiec BA, Rizvi SAA, Do DP. Formulation Development and In vitro Evaluation of Oral Extended-release Capsules Containing Biodegradable Microspheres. J NanomedNanotechnol. 2014;5:208.
3. Nagesh R Sandu, SP Senthil, KL Senthi. Preparation, Characterisation and In-Vitro Study of Microspheres Containing ImatinibMesylate by Solvent Evaporation Technique Using Ethyl Cellulose. RRJPPS. 2013;2:1-6.
4. Mahesh S Nemade, Rajesh Y Chaudhari, Vijay R Patil. Preparation and Characterization of Tegaserod Maleate Containing Targeted Microspheres for Colonic Drug Delivery System. RRJPPS. 2014;3:1-6.
5. Hereba AT, Elblbesy MA, Shawki MM. Study of the Effect of Magnetic Microspheres on Some Biophysical Parameters of Human Blood (In vitro Study). J BiotechnolBiomater. 2012;2:135.
6. Akash MSH et al. Characterization of Ethylcellulose and Hydroxypropyl Methylcellulose Microspheres for Controlled Release of Flurbiprofen. J Pharm Drug Deliv Res. 2013;2:1.
7. Nanjwade BK, Bechra HM, Nanjwade VK, Derkar GK, Manvi FV. Formulation and Characterization of Hydralazine Hydrochloride Biodegraded Microspheres for Intramuscular Administration. J Bioanal Biomed. 2011;3:032-037.
8. Nanjwade BK et al. Development and Evaluation of Intranasal Mucoadhesiv Microspheres of Neostigmine Bromide. Pharm Anal Acta. 2011;2:118.
9. El-Bary AA, El-Gazayerly O, El-Hagrasy A, Ad-din IS. Preparation of ZaleplonMicroparticles Using Emulsion Solvent Diffusion Technique. J Pharm Drug Deliv Res. 2012:1:3.
10. Ettorre GM et al. Experiences in Hepatic Surgery and Transplantation after Radioembolization. J Nucl Med RadiatTher. 2011;2:109.
11. Enriquez GG, Orawiec BA, Rizvi SAA, Do DP. Formulation Development and In vitro Evaluation of Oral Extended-release Capsules Containing Biodegradable Microspheres. J NanomedNanotechnol. 2014;5:208.
12. Kokardekar RR, Chaudhari YS, Kumavat SD Pawar HA. Development and Evaluation of Sustained Release Microspheres of Glibenclamide by Emulsion Solvent Evaporation Method. ClinPharmacolBiopharm. 2014;4:127.
13. Sanjay R Patel and Vipul P Patel. In-Vitro Drug Release Studies Of Insulin Loaded Eudrajit L Microspheres. RRJPPS. 2013;2:1-5.
14. Ghahramani MR, Garibov AA, Agayev TN. Determination of Radiochemical Purity of Radioactive Microspheres by Paper Chromatography. J Chromatogr Sep Tech. 2014;6:258.
15. Dawei Qi etal. Development of Deuterated- Leucine Labeling with Immunoprecipitation to Analyze Cellular Protein Complex. J Proteomics Bioinform. 2008;1:346-358.
16. Chang E et al. Biodegradable PLGA-Based Drug Delivery Systems for Modulating Ocular Surface Disease under Experimental Murine Dry Eye. J Clinic Experiment Ophthalmol. 2011;2:191.
17. Nemethova V, Lacik I, Razga F. Vibration Technology for Microencapsulation: The Restrictive Role of Viscosity. J Bioprocess Biotech. 2015;5:199.
18. Barakat NS, Al-Shazli G, Almedany AH. Development of Novel Controlled Release Gliclazide-Loaded poly(e-caprolactone) Microparticles: Effect of Polymer Blends. Pharm Anal Acta. 2012;3:150.
19. Gavasane AJ and Pawar HA. Synthetic Biodegradable Polymers Used in Controlled Drug Delivery System: An Overview. ClinPharmacolBiopharm. 2014;3:121.
20. Mahesh S Nemade, Rajesh Y Chaudhari, Vijay R Patil. Preparation and Characterization of Tegaserod Maleate Containing Targeted Microspheres for Colonic Drug Delivery System. RRJPPS. 2014;3:1-6.
21. Koloukani SA, Cao A, Cao Q. Radioembolization of Yttrium-90 Microspheres for Clinical Treatment of Hepatic Malignancy. J Nucl Med RadiatTher. 2014;5:187.
22. Patel Manish P, Patel Jayvadan K, Patel Ravi R, Patel Kalpesh N. Microencapsulation of Verapamil Hydrochloride: A Novel Approach for Gastric Retention Using Different Polymers. Med chem. 2012;2:076-080.
23. Hereba AT, Elblbesy MA, Shawki MM. Study of the Effect of Magnetic Microspheres on Some Biophysical Parameters of Human Blood (In vitro Study). J BiotechnolBiomater. 2012;2:135.
24. Parul K Patel and Pandya SS. Preparation and Characterization of Crosslinked Gum Acacia Microspheres by Single Step Emulsion In-Situ Polymer Crosslinking Method: A Potential Vehicle for Controlled Drug Delivery. RRJPPS. 2013;2:1-8.
25. Bharat W Tekade, Umesh T Jadhao, Vinod M Thakare, Kundan P Chaudhari, Harshal B KedareFormulation and Evaluation of Metoclopramide Hydrochloride Sustained Release Microsphere. RRJPPS. 2013;3:1-10.